The present invention relates generally to ultrawideband (UWB) communications, and more particularly to automatic gain control (AGC) in a receiver of UWB communications.
UWB communication systems communicate information using what may be considered a large portion of frequency spectrum. For example, UWB systems may use frequencies between 3.1-10.6 GHz. This portion of the frequency spectrum may also be used by other communication systems.
Many proposed UWB systems are expected to use orthogonal frequency division multiplexing (OFDM). An OFDM carrier signal is the sum of a number of orthogonal subcarriers. Baseband data on each subcarrier is independently modulated. An example of OFDM symbol structure and frequency hopping patterns are disclosed in Multiband OFDM Physical Layer Specification, Release 1.0, Jan. 14, 2005, which is incorporated herein by reference.
A receiver of an OFDM UWB communication performs a variety of signal processing operations on the OFDM symbols received. The signal including the OFDM symbols may have range of levels or strengths over the specturm of the UWB communication. The signal processing steps or components may each impart a gain to the signal and the gain may vary depending on the frequency of each portion of the signal. Changes in the input signal level as a function of frequency may distort the signal and impair further processing steps. Appropriately setting the gain of a received signal is therefore of some importance. Unfortunately, UWB transmissions may be bursty, or considered bursty in view of potential frequency hopping, limiting time for performing automatic gain control (AGC) operations and also potentially increasing the difficulty of performing such operations.